Humidity regulated drier



A. BARNSTEINER I-IUMIDI'IY` REGULATED DRIER Filed Feb. 14, 1934 Heating gj/32 Regi/W5 WITNESSES:

Saz/m9 af Pa wel* TTOR'NEY My-f Patented Aug. l1, 1936 UNITED STATES PATENT OFFICE HUMIDITY REGULATED DRIER Pennsylvania Application February 14, 1934, Serial No. 711,181 2 Claims. (Cl. 34-19) My linvention, relates to drying devices and it has particular relation to compartment or oven type driers which utilize circulations or changes of air to effect removal of moisture from materials placed therein.

In the operation of laundry driers, and other moisture-removing compartments of the type under consideration, I have discovered that when the humidity of the incoming air is below a certain value, as is the case on dry days, satisfactory results may be obtained by merely circulating the air through the clothes or other articles to be dried. However, when, as on damp days, the moisture content of the incoming air is above this value, a pre-drying of such air is essential for effective operation of the device.

While the use of electric and other heaters to effect such pre-drying has for some time been practiced, thefact that on dry days utilization of such heaters can be dispensed with has not been so generally taken advantage of. It will, however, be apparent that in the interests of economy the source of heat preferably should be brought into action only on damp days when pre-drying of the circulated air is essential.

In the laundry drier situation specifically mentioned, to expect the housewife to accurately judge of the humidity conditions in order to manually control the heaters is decidedly impractical. Means for automatically controlling these heaters in accordance with air humidity are, therefore, needed in this and other comparable applications. It is to the provision of such means that my invention is directed.

One object of my invention is to increase the economy of operation of compartment drying devices through which is circulated air of widely varying moisture contents.

Another object of my invention is to provide, in drying devices of the type under consideration, an air humidity responsive system for automatically controlling energization of the air preheaters.

My invention itself, together with additional objects and advantages thereof, will best be understood through the following description of a specific embodiment when taken in conjunction with the accompanying drawing, in which:

Figure 1 is a perspective view of a cabinettype laundry drier to which the humidity-responsive heater control system of my invention is' shown as being applied; and

Fig, 2 is a diagram showing one preferred manner in which the individual devices comprised by the equipment illustrated in Fig. 1 are interconnected to effect the desired automatic control functions.

While I am illustrating my invention as applied to an electrically heated laundry drier, it will be understood that it is equally applicable to driers of other types, such, for example, as oven or compartment devices of all kinds, Whether of the extensible-rack, side-swinging door, or other construction. Its application is not restricted by the nature of the material to be dried, nor by the character of the source of air predrying heat or its method of adjustment.

Referring to the drawing, and particularly to Fig. 1 thereof, the laundry drier there shown is illustrated as comprising a sheet metal cabinet l0, which is provided with extensible rack units l2 and I4 adapted for independent withdrawal from the cabinet structure to permit the hanging, upon bar members I 6 thereof, of clothes or other moisture carrying materials which it is desired to dry. When closed, these rack units effectively seal the cabinet from the entrance of air around the openings provided therefor.

In the end of the lower portion of the main cabinet I0 is installed an inspection door I8 shown in the open position. Inside of the door opening there is providedan air inlet duct 20 whch constitutes the terminus of a supply conduit 22 which may be arranged to supply air from any desired location, such, for example, as from the outside u of the house or from some point in the laundry room. Over the top of the cabinet proper is positioned a discharge chamber or hood 24, by means of which air from the interior of the compartment may be drawn, by a motor-driven exhaust fan 28, through openings 26 and discharged to the outside through an outlet aperture 30.

With the extensible racks l2 and I4 and the door I8 closed, operation of this fan 28 thus draws air through the conduit 22 and past the damp .articles suspended from the racks on the inside of the cabinet IIJ. Inrorder to pre-heat the incoming air when it is suiciently damp to make it necessary, there are provided in the lower portion of the drier cabinet Ill heating means in the form of electrical resistors 32 supported in any suitable manner, as by side members 34, suitably insulated from casing I 0.

To automatically control the energizatlon of these heaters in accordance with the humidity of the incoming air, I provide in the inlet duct 20 of the drier cabinet a humldostat 36 which is sensitive to the moisture content of the air flowing past it. This humidostat may be any one of a number of types well known in the art which functions to actuate a set of electrical contacts when the air humidity increases or decreases beyond a predetermined value.

One preferred manner of interconnecting, in accordance with my invention, the devices which have just been described is shown diagrammatically in Fig. 2, in which a source of energization for the heating resistors 32, the fan driving motor 38, and the required control circuits, is represented by circuit conductors 40. In the ,particular connection illustrated a main operation control switch 42 is utilized in the heater and thefan supply circuits, and an auxiliary switch 44 is also connected in the fan supply circuit for a purpose to be explained.

The switch 42, which acts to adjust the heat intensity in addition to controlling the drier operation, may be a well known multi-position type represented in Fig. 1 as having an actuating knob which protrudes from the face of a small boxlike structure 50 mounted on the drier cabinet I8. This compartment additionally houses a control relay 46 which is connected in the heater circuit as shown in Fig. 2. It also provides a mounting for the auxiliary switch 44, together with an indicating lamp 52 which may be arranged to'light whenever the relay 46, which is responsive to the humidostat 36, is biased to the actuated or closed-circuit position.

One preferred form of heater-control humidostat (device 36) is diagrammatically represented in Fig. 2 as comprising a moisture sensitive element 60 which may be in the form of a strand of human hair or other material having the characteristic, when placed under tension, of appreciably lengthening when the moisture content of the surrounding air is raised, and of contracting when the moisture content of the air is reduced. In the illustrated device, the required tension is supplied by means of a spring 62. Actuated by these changes in length of the element 60 is a centrally pivoted lever 64 carrying on one end a contact member 66 which when the element 60 contracts is biased, through a toggle arrangement completed by a flat spring 68, to a lower position, and when the element 60 expands is biased upwardly into engagement with a stationary contact member 12. Calibration of the instrument may be changed by adjusting a tension screw 99.

In the operation of the complete automatic control system shown in Fig. 2, movement of the blades of the switch 42 upwardly from the oi position shown to its first operative position energizes the motor 38, which drives the fan 2B, to draw air through the drying compartment. The

motor energizing circuit may be traced from the upper power source conductor 49, through conductor 90, the blade 9| of switch 42, conductors 14 and 92, the motor 38, and conductor 93 bac to the lower power source conductor 49.

If the air entering the compartment, which air ows past the humidostat 36, is of a proper degree of dryness, the humidostat contact members will remain in the disengaged position illustrated. The circuit for the actuating winding of relay 46 being incomplete, no energization of the heating resistors can, under these conditions, be eilected.

However, if the incomingA air contains above a predetermined amount of moisture, the element 60 of the humidostat expands and contact member 66 is actuated upwardly into engagement with member 12, thereby completing an actuating circuit for relay 46. This circuit may be traced from the upper power source conductor 40 through the fan motor control blade 9i, conductor 95, contact members 12 and 66, the actuating winding 16 of relay 46, and conductor 18, back to the lower power source conductor 49.

Thus energized, relay 46 actuates its contact 5 member 8D upwardly and completes an energizing circuit for the heating resistors 32, which circuit may be traced from the upper power source conductor 40 through conductor 82, the resistors 32, the blade 91 of the heat adjusting control switch 42, conductor 84, the relay contact member 80, and conductor 18, back to the lower power source conductor 40. Thus energized, the resistors produce heat to pre-dry air in the drier cabinet. 1

In the particular circuits shown, the intensity of heat produced by the resistors depends upon the position of the blades 91 and 98 of adjusting switch 42. As the proper position will in general depend upon the amount of clothes which are o introduced into the drier cabinet and also upon other comparable conditions, the setting can best be determined by experimentation.

When the switch blades are actuated to the rst operative position, there is set up a circuit for the heating resistors 32 which, upon the actuation of relay 46, causes them to produce a low value of heat, the sections above and below the conductor 83, in the diagram, being energized in series by the power circuit 40. Actuation of the switch to the second operative position increases the heat ,intensity by placing full voltage across the lower resistor sections, and when the blades occupy the top or third operative position, both the upper and lower resistor sections are energized by full voltage and hence produce their maximum output. The illustrated switch connection will thus be recognized as comprising a well known series-parallel arrangement of resistor sections.

When it is desired merely to opeate the fan and thereby draw air from the laundry room through the drier for discharge to the outside to eiect ventilation only, the switch 42 is placed in the lower or off position illustrated, in which 4 no energization of the resistor is possible, and the auxiliary switch 44 is closed to independently complete the fan motor circuit.

As before mentioned, the indicating lamp 52 lights whenever the relay 46 is biased to the actuated position, and thereby indicates when the incoming air circulated by the fan 28 is sulciently damp as to require the use of the pre, drying heaters 32. It will be noted that heater energization or lamp indication can be effected only when the exhaust fan motor is energized. This particular precaution is believed of value, inasmuch as heater operation in the absence of air circulation would subject clothing within the cabinet to danger from burning due to accumulation of heat in the unventilated closed compartment.

Although I have shown and described a certain specific embodiment of my invention, I am fully aware that many modications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the scope of the appended claims.

I claim as my invention:

1. In a drier adapted to remove moisture from articles placed therein by eiecting a circulation of air past and through said articles, the combination of means for heating the fresh air which is taken into the drier, and a humidostat, placed 75 in the path of said indrawn fresh air in advance of its Contact with the said heating means or the said articles, for controlling the operation of said heating means.

2. In a drier adapted to remove moisture from articles placed therein by effecting a circulation of air past and through said articles, the combination of an electric heater positioned Within the drier to raise the temperature of the fresh air drawn therein, a source of energization for said heater. a humidostat placed in the path of said indrawn fresh air to be sensitive to the moisture content thereof before the air contacts the said heater or the said articles, and means controlled by said humidostat for completing a connection of the heater with its source of energization when the said moisture content exceeds a given value,

ALFONS BARNSTEINER. 

